The most conventional bidirectional switches are triacs. A triac corresponds to the antiparallel association of two thyristors. It may be directly connected in an alternating current (A.C.) network, for example, the mains. The gate of a conventional triac corresponds to the cathode gate of one at least of the two thyristors forming it and is referenced to the main electrode (or power conduction electrode) located on the front surface of this triac, that is, the surface which comprises the gate electrode, the main electrode (or power conduction electrode) located on the other surface of the triac, or rear surface, receiving the power signal.
Bidirectional switches of the type described in U.S. Pat. Nos. 6,034,381, 6,593,600, 6,380,565 and 6,818,927 (incorporated by reference), which are turned on by application of a voltage between a gate electrode located on the front surface of the component and a main electrode located on the opposite surface or rear surface of the component, will be more particularly considered hereafter.
FIG. 1 shows an equivalent electric diagram of such a bidirectional switch. A switch control electrode G is connected to the emitter of a bipolar transistor T having its collector connected to the anode gates of first and second thyristors Th1 and Th2 placed in antiparallel between two main electrodes A1 and A2. Electrode A1 is connected to the anode of thyristor Th1 and to the cathode of thyristor Th2. Electrode A1 is also connected to the base of transistor T. Electrode A2 is connected to the anode of thyristor Th2 and to the cathode of thyristor Th1.